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https://www.cnblogs.com/fillPv/p/5009737.html
avro是一个数据序列化框架，可以高效得进行序列化和反序列化，支持C, C++, C#, Java, PHP, Python, 和Ruby语言。现在使用Java来读写。
环境搭建
1、下载avro-1.7.7.jar and avro-tools-1.7.7.jar两个jar包，放到指定文件目录。下载地址 http://www.trieuvan.com/apache/avro/avro-1.7.7/java/
我放到了D:\soft\avro 文件夹，在改目录下新建java文件夹，用来存放生成的Java代码
2、该目录下新建user.avsc文件，内容是：
user.avsc
{
"type": "record",
"name": "User",
"namespace":"com.test.avro",
"aliases": ["User1","User2"],
"fields" : [
{"name": "name", "type": "string"},
{"name": "age", "type": "int","default":10},
{"name": "email", "type": "string"}
]
}打开cmd，进入到该目录,执行命令生成User类,注意命令后面有个”.”，表示生成的代码放在本目录下。
java -jar avro-tools-1.7.7.jar compile schema user.avsc java .
---result---
Input files to compile:
user.avsc在该文件夹下的Java文件下的../example/avro/目录下就会生成User.java文件。
使用eclipse新建maven项目，在pom.xml加入avro的依赖。
<dependency>
<groupId>org.apache.avro</groupId>
<artifactId>avro</artifactId>
<version>1.7.7</version>
</dependency>生成的User.java文件的内容如下。
把生成的User.java类复制到工程中，注意这个User.java里面生成的User类及其内部类的包名默认是user.avsc文件中的namespace的值，
User.java
package com.paloaltonetworks.schemaregistry.serializers;
/**
* Autogenerated by Avro
*
* DO NOT EDIT DIRECTLY
*/
@SuppressWarnings("all")
@org.apache.avro.specific.AvroGenerated
public class User extends org.apache.avro.specific.SpecificRecordBase implements org.apache.avro.specific.SpecificRecord {
public static final org.apache.avro.Schema SCHEMA$ = new org.apache.avro.Schema.Parser().parse("{\"type\":\"record\",\"name\":\"User\",\"namespace\":\"example.avro\",\"fields\":[{\"name\":\"name\",\"type\":\"string\"},{\"name\":\"age\",\"type\":\"int\"},{\"name\":\"email\",\"type\":\"string\"}]}");
public static org.apache.avro.Schema getClassSchema() { return SCHEMA$; }
@Deprecated public java.lang.CharSequence name;
@Deprecated public java.lang.Integer age;
@Deprecated public java.lang.CharSequence email;
/**
* Default constructor. Note that this does not initialize fields
* to their default values from the schema. If that is desired then
* one should use <code>newBuilder()</code>.
*/
public User() {}
/**
* All-args constructor.
*/
public User(java.lang.CharSequence name, java.lang.Integer age, java.lang.CharSequence email) {
this.name = name;
this.age = age;
this.email = email;
}
public org.apache.avro.Schema getSchema() { return SCHEMA$; }
// Used by DatumWriter. Applications should not call.
public java.lang.Object get(int field$) {
switch (field$) {
case 0: return name;
case 1: return age;
case 2: return email;
default: throw new org.apache.avro.AvroRuntimeException("Bad index");
}
}
// Used by DatumReader. Applications should not call.
@SuppressWarnings(value="unchecked")
public void put(int field$, java.lang.Object value$) {
switch (field$) {
case 0: name = (java.lang.CharSequence)value$; break;
case 1: age = (java.lang.Integer)value$; break;
case 2: email = (java.lang.CharSequence)value$; break;
default: throw new org.apache.avro.AvroRuntimeException("Bad index");
}
}
/**
* Gets the value of the 'name' field.
*/
public java.lang.CharSequence getName() {
return name;
}
/**
* Sets the value of the 'name' field.
* @param value the value to set.
*/
public void setName(java.lang.CharSequence value) {
this.name = value;
}
/**
* Gets the value of the 'age' field.
*/
public java.lang.Integer getAge() {
return age;
}
/**
* Sets the value of the 'age' field.
* @param value the value to set.
*/
public void setAge(java.lang.Integer value) {
this.age = value;
}
/**
* Gets the value of the 'email' field.
*/
public java.lang.CharSequence getEmail() {
return email;
}
/**
* Sets the value of the 'email' field.
* @param value the value to set.
*/
public void setEmail(java.lang.CharSequence value) {
this.email = value;
}
/** Creates a new User RecordBuilder */
public static User.Builder newBuilder() {
return new User.Builder();
}
/** Creates a new User RecordBuilder by copying an existing Builder */
public static User.Builder newBuilder(User.Builder other) {
return new User.Builder(other);
}
/** Creates a new User RecordBuilder by copying an existing User instance */
public static User.Builder newBuilder(User other) {
return new User.Builder(other);
}
/**
* RecordBuilder for User instances.
*/
public static class Builder extends org.apache.avro.specific.SpecificRecordBuilderBase<User>
implements org.apache.avro.data.RecordBuilder<User> {
private java.lang.CharSequence name;
private java.lang.Integer age;
private java.lang.CharSequence email;
/** Creates a new Builder */
private Builder() {
super(User.SCHEMA$);
}
/** Creates a Builder by copying an existing Builder */
private Builder(User.Builder other) {
super(other);
if (isValidValue(fields()[0], other.name)) {
this.name = data().deepCopy(fields()[0].schema(), other.name);
fieldSetFlags()[0] = true;
}
if (isValidValue(fields()[1], other.age)) {
this.age = data().deepCopy(fields()[1].schema(), other.age);
fieldSetFlags()[1] = true;
}
if (isValidValue(fields()[2], other.email)) {
this.email = data().deepCopy(fields()[2].schema(), other.email);
fieldSetFlags()[2] = true;
}
}
/** Creates a Builder by copying an existing User instance */
private Builder(User other) {
super(User.SCHEMA$);
if (isValidValue(fields()[0], other.name)) {
this.name = data().deepCopy(fields()[0].schema(), other.name);
fieldSetFlags()[0] = true;
}
if (isValidValue(fields()[1], other.age)) {
this.age = data().deepCopy(fields()[1].schema(), other.age);
fieldSetFlags()[1] = true;
}
if (isValidValue(fields()[2], other.email)) {
this.email = data().deepCopy(fields()[2].schema(), other.email);
fieldSetFlags()[2] = true;
}
}
/** Gets the value of the 'name' field */
public java.lang.CharSequence getName() {
return name;
}
/** Sets the value of the 'name' field */
public User.Builder setName(java.lang.CharSequence value) {
validate(fields()[0], value);
this.name = value;
fieldSetFlags()[0] = true;
return this;
}
/** Checks whether the 'name' field has been set */
public boolean hasName() {
return fieldSetFlags()[0];
}
/** Clears the value of the 'name' field */
public User.Builder clearName() {
name = null;
fieldSetFlags()[0] = false;
return this;
}
/** Gets the value of the 'age' field */
public java.lang.Integer getAge() {
return age;
}
/** Sets the value of the 'age' field */
public User.Builder setAge(java.lang.Integer value) {
validate(fields()[1], value);
this.age = value;
fieldSetFlags()[1] = true;
return this;
}
/** Checks whether the 'age' field has been set */
public boolean hasAge() {
return fieldSetFlags()[1];
}
/** Clears the value of the 'age' field */
public User.Builder clearAge() {
email = null;
fieldSetFlags()[1] = false;
return this;
}
/** Gets the value of the 'email' field */
public java.lang.CharSequence getEmail() {
return email;
}
/** Sets the value of the 'email' field */
public User.Builder setEmail(java.lang.CharSequence value) {
validate(fields()[2], value);
this.email = value;
fieldSetFlags()[2] = true;
return this;
}
/** Checks whether the 'email' field has been set */
public boolean hasEmail() {
return fieldSetFlags()[2];
}
/** Clears the value of the 'email' field */
public User.Builder clearEmail() {
email = null;
fieldSetFlags()[2] = false;
return this;
}
@Override
public User build() {
try {
User record = new User();
record.name = fieldSetFlags()[0] ? this.name : (java.lang.CharSequence) defaultValue(fields()[0]);
record.age = fieldSetFlags()[1] ? this.age : (java.lang.Integer) defaultValue(fields()[1]);
record.email = fieldSetFlags()[2] ? this.email : (java.lang.CharSequence) defaultValue(fields()[2]);
return record;
} catch (Exception e) {
throw new org.apache.avro.AvroRuntimeException(e);
}
}
}
}Main.java
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.io.BinaryEncoder;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.io.EncoderFactory;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificDatumWriter;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
// 声明并初始化User对象
String path = "/Users/shahuang/Documents/git/wf3lab/schemaregistry/javaclient/data/user2.avro"; // avro文件存放目录
// 方式一
User user1 = new User();
user1.setName("zhangsan");
user1.setAge(21);
user1.setEmail("email");
// 方式二 使用构造函数
// Alternate constructor
User user2 = new User("Ben", 7, "red");
// 方式三，使用Build方式
// Construct via builder
User user3 = User.newBuilder()
.setName("Charlie")
.setEmail("blue")
.setAge(22)
.build();
// byte[] data = datafwriter(user1);
byte[] data = Bencode(user1);
for (byte x : data) {
System.out.print((char)x);
}
DatumReader<User> reader = new SpecificDatumReader<User>(User.class);
DataFileReader<User> dataFileReader = new DataFileReader<User>(new File(path), reader);
User user = null;
while (dataFileReader.hasNext()) {
user = dataFileReader.next();
System.out.println(user);
}
}
// 只serialize data到byte[]
public static byte[] datafwriter(User user1) throws IOException {
DatumWriter<User> userDatumWriter = new SpecificDatumWriter<User>(User.class);
DataFileWriter<User> dataFileWriter = new DataFileWriter<User>(userDatumWriter);
ByteArrayOutputStream bout = new ByteArrayOutputStream();
dataFileWriter.create(user1.getSchema(), bout);
// 把生成的user对象写入到avro文件
dataFileWriter.append(user1);
dataFileWriter.close();
byte[] data = bout.toByteArray();
return data;
}
// serialize data and add schema at front
public static byte[] Bencode(User msg) throws IOException {
DatumWriter<User> writer;
ByteArrayOutputStream baos;
writer = new SpecificDatumWriter<User>(User.getClassSchema());
baos = new ByteArrayOutputStream();
baos.reset();
BinaryEncoder encoder = EncoderFactory.get().binaryEncoder(baos, null);
writer.write(msg, encoder);
encoder.flush();
baos.flush();
return baos.toByteArray();
}
}
Result
{"name": "zhangsan", "age": 21, "email": "email"}
{"name": "Ben", "age": 7, "email": "red"}
{"name": "Charlie", "age": 22, "email": "blue"}